The danger President Trump faces from the various investigations into the Trump-Russia matter has changed dramatically in recent weeks. If you're a Republican and you still believe the critical question is whether Trump or his associates colluded with Russians to influence the 2016 election -- if you still think that, you're behind the times. So now, a few notes on where the Trump affair is today:

1. It's not about collusion anymore.

Fired FBI Director James Comey's testimony before the Senate Intelligence Committee marked the full shift of the Trump-Russia investigation from a probe dedicated to discovering collusion to a probe dedicated to proving the president obstructed justice.

Democrats at the Comey hearing barely touched on the collusion issue, which appears to have turned out to be a dry hole.

But to Democrats, that no longer matters. Now, it's all about obstruction of justice. While Comey testified that President Trump was never under investigation in the FBI counterintelligence probe under Comey, now, after the Comey memos and the Comey firing, it seems safe to predict that special counsel Robert Mueller will investigate Trump for obstruction. So it is a new game, even if Republicans keep trying to play the old one.

2. Trump failed to take the threat against him seriously.

Here is a simple fact: Many of Trump's most determined adversaries do not want just to defeat him on Obamacare, although they want that, too. They do not want just to defeat him on taxes, although they want that, too. No, they do not want just to defeat him -- they want to remove him from office.

That has been clear from the moment The Associated Press called the presidential race for Trump in the early hours of Nov. 9. Some of those adversaries began discussing ways to remove Trump that very day. Some Democrats have been talking about it ever since.

What seems clear, though, is that Trump never, at least until now, took the threat terribly seriously. Whether from his own belief that he can persuade people to like him, or his faith in his ability to do business with a wide variety of players -- for whatever reason, Trump has acted as if he is not every day in mortal threat from opponents who want to remove him from office. He has given them ammunition left and right and then complained that they are using it.

3. The future is in Robert Mueller's hands.

There are a few models for how the Mueller investigation might play out. Perhaps the most relevant is the Patrick Fitzgerald-Plamegate investigation of the George W. Bush years. There was an underlying crime in that matter -- the leak of CIA employee Valerie Plame's identity -- but Fitzgerald knew who did it even as he started the investigation. Fitzgerald never prosecuted that person or anybody else for an underlying crime, and instead spent more than three years dragging Bush figures before a grand jury and finally prosecuting one, Lewis Libby, for perjury and obstruction.

Mueller could certainly follow that path if he chooses. But some on Team Trump believe that he won't, given a career they believe shows good judgment and a straight-down-the-line-not-a-zealot-like-Fitzgerald style. But that could be just hope, and in any event, the final decision will be Mueller's.

4. More evidence? Democrats don't need any more to impeach.

How many times have you heard a Democrat or Trump critic say that the Russia investigation is "just getting started" or that they are determined to "get to the bottom" of it? With a new prosecutor starting an open-ended investigation, they're hoping for years of happy hunting. But the fact is, Democrats do not need any more information than what is already publicly known to pursue impeachment proceedings against the president. What they need is 218 votes in the House of Representatives. If they had majority control of the House now, they would already be pursuing impeachment. Which means ...

5. 2018 is everything.

In 2006, when the Iraq War was going disastrously and George W. Bush was at a low point, some Democrats hoped they would not only win control of the House in that year's midterm elections, but that they could then impeach Bush, as well. But even though Bush was in political trouble, Nancy Pelosi, who stood to become speaker if Democrats won, was wary of making the 2006 midterms a referendum on impeachment. Knowing that voters want to vote for something more positive than punishing a president, Pelosi flatly declared before the election that if Democrats prevailed, impeachment would be "off the table." As it turned out, she won big, became speaker, and impeachment stayed off the table.

Now, Democrats have a new class of impeachment enthusiasts who want to go after Trump as soon as possible. And Pelosi, who likely would again become speaker if Democrats take the House in 2018, is again counseling caution.

Whatever the case, the bottom line next year is 218 votes. If Democrats have them, the president's life becomes much, much more difficult and fraught with danger.